North Korea announces restart of all nuclear facilities

North Korea has announced it is "readjusting and restarting" all facilities at its main Yongbyon nuclear complex, including a mothballed reactor, signalling it will also be openly enriching weapons-grade uranium.

A spokesman from the North's atomic energy said all of the country's nuclear facilities - including its uranium enrichment facility and the five-megawatt Yongbyon reactor which it closed in 2007 - would be restarted.

The spokesman, quoted by the KCNA state media agency, said the move was being made in line with a policy of "bolstering the nuclear armed force both in quality and quantity" as well as solving "acute" electricity shortages.

The Yongbyon reactor - the sole source of plutonium for Pyongyang's nuclear weapons program - was shut down in 2007 under a program that saw the North receive aid from six nations for disarming its nuclear facilities.

The reactor's cooling tower was destroyed in the following summer.

It is believed the country has enough stockpiled plutonium for four to eight bombs but many believe the North has also been secretly enriching weapons-grade uranium at the Yongbyon complex for years.

North Korea revealed it was enriching uranium in Yongbyon in 2010 when it allowed foreign experts to visit the centrifuge facility there but insisted it was solely low-level enrichment for energy purposes.

Pyongyang has launched relentless verbal attacks and threats against the United States and South Korea since new UN sanctions punishing it for its February nuclear test were adopted and during military drills by the South and US forces.

China has called for restraint following the latest announcement while the South Korean foreign ministry said the news was "very regrettable".

"The North should honour agreements and promises that have been made in the past... we will closely monitor the situation," a South Korean ministry spokesman said.

'War deterrent'

On Sunday, North Korean leader Kim Jong-un said nuclear capability supported the country's economic development and accused the US of trying to drag the North into an arms race.

"It is on the basis of a strong nuclear strength that peace and prosperity can exist and so can the happiness of people's lives," Jong-un said in the speech delivered to the central committee meeting of the ruling Workers Party of Korea.

Threats from the North have prompted the US to beef up its forces on the Korean peninsula and station a warship off the coast.

North Korea had cut off hotlines between it, the United States, South Korea and the UN and threatened to close a joint economic zone it runs with the South.

It put its missile forces on full alert and threatened US bases in the Pacific and on the mainland.

Jong-un said no nuclear state had been invaded in modern history and that "the greater the nuclear attack capability, the greater the strength of the deterrent against an invasion".

"Our nuclear strength is a reliable war deterrent and a guarantee to protect our sovereignty," he said.